Download MendeleySymport and antiport mechanisms of human glutamate transporters.
Qiu, B., Boudker, O.(2023) Nat Commun 14: 2579-2579
- PubMed: 37142617
- DOI: https://doi.org/10.1038/s41467-023-38120-5
- Primary Citation of Related Structures:
8CTC, 8CTD, 8CUA, 8CUD, 8CUI, 8CUJ, 8CV2, 8CV3 - PubMed Abstract:
Excitatory amino acid transporters (EAATs) uptake glutamate into glial cells and neurons. EAATs achieve million-fold transmitter gradients by symporting it with three sodium ions and a proton, and countertransporting a potassium ion via an elevator mechanism. Despite the availability of structures, the symport and antiport mechanisms still need to be clarified. We report high-resolution cryo-EM structures of human EAAT3 bound to the neurotransmitter glutamate with symported ions, potassium ions, sodium ions alone, or without ligands. We show that an evolutionarily conserved occluded translocation intermediate has a dramatically higher affinity for the neurotransmitter and the countertransported potassium ion than outward- or inward-facing transporters and plays a crucial role in ion coupling. We propose a comprehensive ion coupling mechanism involving a choreographed interplay between bound solutes, conformations of conserved amino acid motifs, and movements of the gating hairpin and the substrate-binding domain.
Organizational Affiliation:
Department of Physiology & Biophysics, Weill Cornell Medicine, 1300 York Ave, New York, NY, 10021, USA. biq2001@med.cornell.edu.
